Duplexing device for transceiver antenna systems



Sept 16, 1952 A. A. VARELA ET A1. 2,611,079

'DUPLEXING DEVICE FOR TRANSCEIVER ANTENNA SYSTEMS.

Filed July 27, 1942 Robert A. Ht-fn ,Jn @M /WW GMM/nw Patented Sept. 16, 1952 UNITED STATES PATENT nTJ-PLEXTNG DEVICE Fon .'rnAnsoElvEa.

ANTENNA SYSTEMS Y Arthur A.' Varela and RobertA. Herring, Jr'.,

Washington, D. C.

npplicatinnaulytzv, 1942,;seria1 NDA-52,534

(C1150-Tar) i .Y (Granted under Vthe act ol.' March 3, 1883, as

8 Claims.

This invention relates broadlyfto an automatic coupling means for vtransceiver antenna systems and .more particularlyk to a .means facilitating the use of asingle antenna in both the transmission Y amended April 30, 1928; 370 0. G. 757,)

The devices with which this invention fi's-'-'1co'n'- 'cerned ern-ploy either a spark, va glow-discharge tube or a biased diode as theprimaryswitching Y element and depend on the change of :this-ele#- ment from high resistanceorlowvoltagesito low resistance for .high voltages. llinie-lit-can be 'shownthat the eliiciency oftheV dn-plexing' sys:- tem increases as the circuit impedance-across the y'discharge device in `its -non-conducting state increases. y n .i The'impedance across la `spark gap-or'dode when inserted as part of Vthev innerconductor of4 a vselected length -of resonant concentricfline can be shown to be Aproportional* to: l

a l i, Y

ceiver tubes and useless absorption of power from the transmitter. Such means have been devised and are known to the art.

It is an object -of this invention to provide an improved means-of this type, such improvements including reduction of size, increased eiiiciency in operation and less power dissipation by the `decoupling device, resulting in ionger life of the device.

It is a further object Vof this invention 'to provide a duplexing system, which for a given switching performance and eiiiciency has alower Qy for reception than systems employed heretotore. A high Q system will in many instances alternate the response to short pulses.

It is a more specific object of this invention to provide a transformer for coupling a 'receiver to an antenna transmission line,l which for a given Asize obtains maximum impedance across a discharge device containedtherein, in a nonconducting state and maximum decoupling of the receiver when said device is conducting.

All of the duplexing systems with which this invention is concerned employ a transmission line of an .odd quarter wave length between the main antenna transmission line and the transforming or impedance switching tank. When the transmitter is operating this line resonates and presents a high impedance to the main junction. Decoupling of the receiver from this line Y Section embodying ,the

impedance at the junction and minimum power 1 absorption by the receiver.

on one side of the gap, Lzisthe .length-of the inner Aconductor on the other Side of the, gapand A is the Wave length. Thus, -maX-imum-impedance willroccur at the gap when L1. is equal to Lz. When this conditionis satisedfoptimum eliciencyof the switch-ing; means results.` l

Referring :now-to the drawings: l 1 we Fig. ,1 is an elevationalviewpartlynwcross principles.` ofthis'V :in-

vention; f

Fig. 1a is a graphical representatonfgof:the voltage distributionon theswitching means when the receiver is coupled to the antenna fl Fig. 1b is a graphical representation of th voltage distribution on .the Switching means when thetransmitterjis coupled.v to the antenna, yand Figs. 2 and 3 are `elevational views partly-:incross-section, showing alternate V.arrangements embodying this invention. v

Referring to Fig. 1 in more detail, `the output of transmitter 3 is coupled to ya non-*resonant line 2 which feeds an antenna I5.: Thefjinner and outer conductors of one end of ajquarter wave -matching line l0 are conductivelysecured to thecorresponding conductors of thehmain transmission line -2 at some point lIan oddnumber of quarter wave lengths from transmitter"3.'`

The ,other end of the conductors of-'fniatchln'g line I 0 are conductively secured to the corresponding conductors oi "concentric 'tank-YH, shown in section, at ,Some point 4 .along its axis. 'Tank Il in this case is a little longerthan'A one The concentric tank II is tunable upo .l0 tion of the amount of power dissipated by 'gap l 1 and point 5 is selected so as to esteablish a one- Y.

. at different points along the axis of said line,

to-one coupling between lines I0 and 8 during the quiescent periods of gap 1.

On a received signal the Iimpedances facing one another throughout the arrangement are matched and cause the tank to perform like a tuned transformer. rises gradually from a minimum at yone end to a maximum at the gap I and then falls to a minimum at the other end. Gap I will function as a resonating capacitor between the two sections of the tank and assist inthe production of a one-to-one coupling between points 4 and 5.as illustrated bythe graph of Fig. 1a. ,f i

Upon operation of transmitterl 3- gap 'I res and forfeits itshigh impedance. The input im- 'I'he impedance ofthe tank pedence at `rpoint 4 will then diminish to' some value R-I-JX. Subsequently the impedance at point I will increase by an amount suflicient to satisfy a characteristic impedance equation of a quarter matching section such as line I0. 'I'his increase of impedance at point I prevents a large amount of power from ilowing into tank I I from line 2. 'I'he voltage on the tank, in this case, will appear similar to that shown by Fig. lb. It is therefore obvious that the coupling between points 4 and 5 has decreasedrconsiderably.

Fig. 2 shows an alternate method of decoupling the receiver from the antenna. Quarter Wave line III joins the receiver line 8 and concentric tank II to the transmission line 2 at point I. Upon the firing of the gap 'I, series capacitor I2`reso`v nates with the reactance of its lead and the tank. The voltage at I3 will then fall to some value lower than' that at I4 resulting in a small ratio of coupling'between-the receiver and antenna. Whether there are any` advantages of this arrangement over that shown in Fig. 1 ldepends mainly on the frequency, power and spark gap capacitance.`

'Another alternate arrangement is shown by Fig. 3. An auxiliary tank .I I isgused to decouple the transmitter to prevent absorption of power during operation of the receiver. Lines I0 and IU join their respective impedance tanks to transmission line 2 at points I and Idisplaced one from another by one-quarter wave length. The operation of tank I I' is similar to I I in that it will offer a high impedance to the passage of low radio frequency voltages at point I' when the gap 'I' is conducting, and a low impedance when the gap is notconducting.

Although several embodiments of the present invention have been disclosed and described herein it is expressly understood that various changes and substitutions may be made therein without departing from the spirit ofthe invention as well understood by those skilled inthe art. Reference therefore will be had to the appended claims for a definition of the limits of the invention.

i. The invention described herein may be manufactured and used by or for the Government of the United States `of America for governmental 4 purposes without the payment of any royalties thereon or therefor.

We claim:

1. In a system having an antenna, a transmitteiga receiver andv a .transmission line coupling vs aid transmitter .to said antenna, means for coupling said receiver to said antenna and for automatically decoupling said receiver from said antenna during operation of said transmitter,

' said means comprising a section of concentric line having a metal conductor short circuiting each end thereof, input and output tap means located the inner conductor of said line being broken at its mid-point'to form a non-linear discharge device, means connecting said input tap means in parallel with said transmission line and means connecting said receiver to said output tap means.

' 2. In a system having an antenna, a transmitter, a receiver and a transmission line coupling said transmitter to said antenna, means for coupling-said receiver to said antenna and for automatically decoupling said receiver from said antenna during operation of said transmitter, said means comprising a'resonant concentric line section having a metal conductor short circuiting each end tehreof, input and'output tap means located at different pointsl along the axis ofl said line, a' spark gap formed at the mid-point of the inner conductor of said line, means connecting said input tap means in parallel with said transmission line and means connecting said receiver to said output tap means.

3. In a system having an antenna, a transmitter, a receiver and a transmission line coupling said transmitter to said antenna, means for coupling said receiver to said antenna and for decoupling said receiver from said antenna during operation of said transmitter, said means comprising a section of concentric line having a metal conductor short circuiting each end thereof, input and output tap means located at different points along the axis of said line to establish a one-.to-one ratio of coupling therebetween on received signals, a spark gap formed at the mid-'- point lof the inner conductor of said line, means connecting said input tap means in parallel with said transmission line and means connecting said receiver to said output tap means.

Y 4. In a system having anantenna, a transmitter, a receiver and a transmission line coupling said transmitter to said antenna, means for coupling said receiver to said antenna and for automatically decoupling said receiver from said antenna during operation of said transmitter, said means comprising a section of concentric line having a metal conductor short circuiting each end thereof, input and output tap means located at different points along the axis of said'line, a spark gap formed at the mid-point'of the inner conductor of said line, a quarter wave matching line section connecting said input tap meansin parallel with said transmission line and means connecting said receiver to said output tap means.

5. In a system having an antenna, a transmitter, a receiver and a transmission line coupling said transmitter to said antenna, means for coupling said receiver to said antenna and for decoupling said receiver from said antenna during operation of said transmitter, said means comprising coupling means from said transmission line to said receiver including a branch trans-l mission line, a section of concentric line havingaf metal conductor short circuiting each end thereof, the inner conductor of said line being broken v at its mid-point to form a non-linear discharge device, input circuit means for said line and means connecting said input circuit means to said branch transmission line.

6. In a system having an antenna, a transmitter, a receiver and a transmission line coupling said transmitter to said antenna, means for coupling said receiver to said antenna and for automatically decoupling said receiver from said antenna during operation of said transmitter, said means comprising coupling means between said transmission line and said receiver including a branch transmission line, a quarter wave length of concentric line having a metal conductor short circuiting each end thereof, a spark gap formed at the mid-point of the inner conduct-or of said line, input tap means located at a point along the axis of said line and means connecting said input tap means to said branch transmission line.

7. In a system having an antenna, a transmitter, a receiver and a transmission line coupling said transmitter to said antenna, means for coupling said receiver to said antenna and for decoupling said receiver from said antenna during operation of said transmitter, said means comprising coupling means between said transmission line and said receiver including a branch transmission line, a section of concentric line having a metal conductor short circuiting each end thereof, a spark gap formed at the mid-point of the inner conductor of said line, input tap means located at a point along the axis of said line and means connecting said input tap means to said branch transmission line at a point thereon spaced from said transmission line by a distance equal to a quarter wave length of the frequency of said transmitter.

8. In a system having an antenna, a transmitter, a receiver and a transmission line coupling said transmitter to said antenna, means for coupling said receiver to said antenna and for automatically decoupling said receiver from said antenna during operation of said transmitter, said means comprising a section of concentric line having a metal conductor short circuiting each end thereof, a spark gap formed at the mid-point of the inner conductor of said 1ine,input tap means located at a point along the axis of said line, a quarter wave length line section having one end thereof connected to said transmission line, means including a capacitance joining said input tap means to the other end of said quarter wave line section and means connecting said receiver to said quarter wave line section.

ARTHUR A. VARELA.

ROBERT A. HERRING, JP..

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,035,958 Girardeau Aug. 20, 1912 1,073,624 Pckerill Sept. 23, 1913 1,304,868 Franklin May 27, 1919 1,872,398 Brown Aug. 16, 1932 2,104,915 Thompson Jan. 11, 1938 2,107,387 Potter Feb. 8, 1938 2,114,114 Roberts Apr. 12, 1938 2,190,668 Llewellyn Feb. 20, 1940 2,202,699 Leeds May 28, 1940 2,202,700 Leeds May 28, 1940 2,239,905 Trevor Apr. 29, 1941 2,241,937 Trevor May 13, 1941 2,250,308 Lindenblad July 22, 1941 2,266,501 Lindenblad Dec. 16, 1941 2,278,210 Morton Mar. 31, 1942 2,301,423 Lindenblad Nov. 10, 1942 2,337,219 Zottu Dec. 21, 1943 2,401,717 Wolff et al. June 4, 1946 2,402,948 Carlson July 2, 1946 2,410,641 Evans Nov. 5, 1946 2,412,161 Patterson Dec. 3, 1946 FOREIGN PATENTS Number Country Date 358,917 Great Britain Oct. 14, 1931 

